The present invention relates to magnetic bases, and relates more particularly to such a magnetic base which comprises a rotary magnetic element, two symmetrical stacks of iron plates covered around tile rotary magnetic element, and two non-magnetic blocks connected between the two stacks of iron plates at different elevations.
FIGS. 1 and 2 show a conventional magnetic base which is comprised of rotary magnetic element 12 turned by a rotary knob, two symmetrical iron blocks 11 covered around the rotary magnetic element 12, two non-magnetic blocks 13 connected between the iron blocks 11 at different elevations. The magnetic flux between the bottom side 15 of the magnetic base and the attracted object 16 is controlled by turning the rotary magnetic element 12. Because the iron blocks 11 are con, only made by forging or milling, when the inside of the iron blocks 11 are magnetically conducted, the magnetic lines of force may be not perpendicular to the axis about which the rotary magnetic element is turned, causing the intensity of the effective magnetic force reduced. Furthermore, because the magnetic field in the magnetic base is irregular, a bow wave loss of the magnetic field tends to occur, causing the force of magnetic attraction weakened.